A proximity touch panel technology which is applicable to display devices is known in the art. The proximity touch panel technology is a technology which, by detecting not only positions in the X and Y directions which are parallel with a panel but also a position in the Z direction which is perpendicular to the panel, enables processing corresponding to an XYZ coordinate position (refer to Non-patent document 1, for example).
One proximity touch panel device is known which calculates a distance between the screen of a display unit and a commanding means (finger, stylus pen, or the like) and changes the contents of a display according to the calculated distance (refer to Patent document 1, for example).